The present invention relates to the general field of dental implants.
More particularly, the invention relates to endo-osseous dental implants and more specifically to the stabilization of these implants.
Presently, endo-osseous implants are conventionally based on the use of an anchoring foot, for example an anchoring screw, adapted so as to be installed in a jaw bone of a patient. This anchoring foot cooperates with an external pillar intended to be fixed in the anchoring foot. The external pillar therefore comprises means for being fixed in the anchoring foot and means for fixing a dental prosthetic element which will cap the external pillar and protrude above the jaw bone of the patient in order to replace the missing dental element. The prosthetic outer pillar is stabilized relatively to the anchoring foot with anti-rotational means with which relative movements of the pillar relatively to this anchoring foot are inhibited.
Further, it is necessary to ensure primary stability of the implant in the bone by ensuring stability of the anchoring foot in the bone. This fact is determining for osteo-integration of the implant. Indeed, masticatory movements of the patient are as many agents for destabilizing this assembly by torsion, rotation, compression, etc., which the implant should be able to withstand.
Thus, two distinct cases occur in the treatment after laying down the anchoring foot.
In the first case, the bone is particularly dense and in a large amount, which unfortunately is rare, and it is then possible to immediately place the prosthetic pillar which is attached on the anchoring foot and to adhesively bond the dental crown on the latter.
In the second case, the anchoring foot is placed <<to be nursed>> during a healing period. This means that the anchoring foot is placed in the bone and the gums are closed over it. In this case, no force is applied and there are no risks of mobilization of the anchoring foot during the healing phase. Thus, a period of six months for a maxillary implant and three months for a mandibular implant is required for allowing healing. During this period, any mobilization or overload of the bone causes rejection of the anchoring foot. After this healing period, the gums are opened and the prosthetic pillar is set into place as well as the tooth.
Therefore, except in cases when the bone has very favorable density and amount, it is not possible to make the tooth during this period of time between three and six months.
Further, with this method, the results obtained on the bone level do not always allow proper stabilization of the implant. This is the case in particular if one is in presence of low density spongy bone, a bone of type 5 for example.
Then, as the primary retention of the implant is a primordial condition for its success, the anchoring foot cannot be left in the mouth and is therefore removed.
Presently, various means are therefore used for stabilizing the anchoring foot of the implant in the second case when bone is not present in a large amount. In particular, increasing the interface between the implant and the bone is sometimes contemplated, for example by a double thread at the surface of the implant or by using nanotechnologies for promoting the formation of a reliable bone interface between the bone of the jaw and the implant by remineralization of the tissues.
It is further noted that it is possible to finally use an exo-osseous implant which will bear upon the sidewalls of the gum while straddling them, in the cases when the bone is very degraded. Such an exo-osseous implant may also comprise an element with an anchor shape. In this case, the implant comprising a plate, a pillar and an anchoring element is designed so as to be installed as an assembly. Typically, the pillar and the anchoring element each interact differently with the plate which will straddle the gum. Anti-rotational means are sometimes borne by the plate and the pillar in order to avoid pivoting of the pillar. This is for example the case in the device described in patent application WO 01/93775.
In known devices, there is no intention of providing the anchoring foot with anti-rotational means. Indeed, it is noted that this is then unnecessary since no movement is able to occur between the plate and the anchoring foot. This solution nevertheless has the disadvantage of having to systematically install the plate/foot/pillar assembly and of not being able to modulate this installation.
In spite of the development of implant technology, it happens that endo-osseous implants continue to have mobility at the end of the healing period and are therefore subject to a lack of osteo-integration.
In view of the foregoing, it is actually seen that there exists a need for improving the stabilization of endo-osseous implants relatively to the jaw bone. Further, if it is possible to increase primary retention of the implant as soon as it is installed, it would be possible, in the majority of the cases, to no longer wait for the end of the healing phase in order to make the prosthetic portion.